CVE-2003-0937 in UnixWare
Summary
by MITRE
SCO UnixWare 7.1.1, 7.1.3, and Open UNIX 8.0.0 allows local users to bypass protections for the "as" address space file for a process ID (PID) by obtaining a procfs file descriptor for the file and calling execve() on a setuid or setgid program, which leaves the descriptor open to the user.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/04/2019
This vulnerability exists in SCO UnixWare and Open UNIX operating systems versions 7.1.1, 7.1.3, and 8.0.0 respectively. The flaw resides in the kernel's handling of process file descriptors within the procfs filesystem, which provides an interface to kernel data structures. When a process attempts to execute a setuid or setgid program, the system fails to properly close or revoke access to the address space file descriptor associated with the process ID. This creates a security boundary violation where local users can exploit the open file descriptor to bypass normal protection mechanisms that should restrict access to sensitive process memory spaces.
The technical implementation of this vulnerability involves the interaction between the procfs filesystem and the execve system call. When a user process calls execve() to execute a setuid or setgid program, the kernel should ensure that all file descriptors associated with the original process are properly closed or restricted. However, in affected versions, the kernel maintains the file descriptor open to the address space file for the process ID, allowing the executing program to retain access to the original process's memory mapping. This represents a classic case of improper privilege management and file descriptor handling that violates fundamental security principles.
The operational impact of this vulnerability is significant for local attackers who can leverage this weakness to gain elevated privileges within the system. By obtaining a procfs file descriptor for a process's address space and then executing a setuid or setgid program, an attacker can maintain access to the original process's memory mappings. This could potentially allow for memory dumping, process injection, or other advanced exploitation techniques that would normally be prevented by proper access controls. The vulnerability essentially creates a persistent access vector that undermines the security model of setuid/setgid programs, which are designed to provide controlled privilege escalation.
From a cybersecurity perspective, this vulnerability aligns with CWE-276, which covers improper file permissions, and represents a failure in the principle of least privilege enforcement. The issue also maps to ATT&CK technique T1068, which involves the use of privilege escalation techniques through improper file permissions and access control mechanisms. Organizations running affected systems should implement immediate mitigations including patching to the latest available security updates from SCO, implementing strict file descriptor access controls, and monitoring for unauthorized access to procfs entries. Additionally, system administrators should consider restricting access to the procfs filesystem and implementing process monitoring to detect suspicious execve operations that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper file descriptor management in kernel space and highlights the need for comprehensive security testing of system call implementations, particularly those involving privilege transitions and process management operations.